audit inventory

Because audit inventory switches perform scheduling based on Layer 2 802.1Q/p CoS markings, it is important that Ethernet frames be correctly marked in campus or branch LANs. However, Layer 2 markings (Ethernet or otherwise) are seldom of end-to-end significance. This is because Layer 2 markings are lost whenever the Layer 2 media changes (for example, from Ethernet to WAN media). In addition, care should be taken that Layer 2 markings are translated to and from Layer 3 markings to ensure consistent end-to-end QoS for the frame or packet, regardless of where it might travel in the network

The Cisco Catalyst 3550 switches offer an 802.1Q tunneling feature that enables service providers to provide Layer 2 VPN tunnels by double-tagging Ethernet frames. As a tunneling technology, this encapsulates traffic from multiple VLANs of one customer with a single service provider tag. It preserves the customer VLAN tag over the service provider network so that the service provider can offer a large number of audit inventory to many customers